ABS resin is widely used in the fields of automobiles, household electric appliances, OA appliances, etc., due to its superior mechanical properties and moldability, but its usages are limited because of insufficient heat resistance and impact strength. On the other hand, polycarbonate (PC) resin is widely used in the fields of automobiles, household electric appliances, precision instruments, etc., due to its superior heat resistance and impact strength, but its usages are limited because of insufficient moldability and impact strength at low temperatures.
As a method for supplementing these drawbacks, it is known to blend an ABS resin and a polycarbonate resin. According to this method, heat resistance and impact strength of an ABS resin are not only improved, but also moldability and impact strength at low temperatures of a polycarbonate resin are improved, and as a result, a blended resin superior in moldability, impact strength, mechanical strength and heat resistance can be obtained. This blended resin made it possible to use in a wide variety of fields such as automobile interior parts, etc., requiring safety of crew members at the time of collision.
However, when the molded articles made of a PC/ABS resin obtained by blending an ABS resin and a polycarbonate resin are used as automobile interior parts, with vibration during car driving, the PC/ABS automobile interior parts come into contact with and rub against each other or other members such as a living sheet or a foam made of ABS resin, acrylic resin, polyvinyl chloride, chloroprene resin, polyurethane, natural rubber, polyester or polyethylene, and squeaking noises (rubbing noises) may be generated. Moreover, when it is used as parts such as a drawer of desks and doors, the PC/ABS parts come into contact with the other members of metallic materials such as SUS, aluminum and brass parts, and ABS resin, squeaking noises (rubbing noises) may be generated. These squeaking noises are a major cause to spoil comfortableness and silence inside cars, offices and houses, and therefore, reduction in squeaking noises is strongly demanded.
Since the above-mentioned PC/ABS resin and polycarbonate resin are amorphous resins, they are higher in coefficient of friction as compared with crystalline resins such as polyethylene, polypropylene, polyacetal and the like. Accordingly, when they are used for a switch part of an instrument panel in an automobile or a slide part of a business desk, etc., fitting with other members, a stick slip phenomenon as illustrated in FIG. 1 occurs to generate unpleasant noises (squeaking noises) because of a large coefficient of friction. The stick slip phenomenon is a phenomenon that is generated when two objects rub against each other. When an object M connected with a spring is placed on a driving table that moves at a driving speed V, as illustrated by a model of FIG. 2(a), the object M moves toward the right direction first as illustrated in FIG. 2(b) together with the table moving at the driving speed V by the action of a static frictional force. When the force by which the object M is to be restored to its original position becomes equal to the static frictional force, the object M starts to slip in the opposite direction to the driving speed V. At this time, the object M comes to receive a kinematic frictional force, and the slip is stopped when the force of the spring becomes equal to the kinematic frictional force as illustrated in FIG. 2(c), so that the object M comes again into a state where it attaches on the driving table and it moves again in the same direction as the driving speed V (FIG. 2(d)). This is called a stick slip phenomenon, and it has been argued that, as illustrated in FIG. 1, if the difference Δμ between the coefficient of static friction μs and the lower end of a saw wavy form μl is large, squeaking noises tend to be generated easily. Meanwhile, a dynamic friction coefficient is a middle value between μs and μl.
Such a squeaking noise is a major cause that spoils comfortableness and silence in cars, offices and houses, and therefore reduction of squeaking noise is demanded strongly.
On the other hand, it is known that the stick slip phenomenon occurs remarkably when the friction velocity dependency of a coefficient of friction determined on the basis of the Amonton-Coulomb's law takes a negative value (see non-patent document 1). Accordingly, it is possible to inhibit the occurrence of the stick slip phenomenon and reduce the generation of squeaking noises by bringing the friction velocity dependency of the coefficient of friction close to zero or by adjusting it to a positive value greater than zero.
Then, in order to prevent such squeaking noises, a method of applying Teflon (registered trademark) coating to the surface of a member, a method of mounting a Teflon (registered trademark) tape, a method of mounting a nonwoven fabric cloth, a method of applying a silicone oil, etc. have been performed. However, the step of mounting or applying is very complicated and requires time and effort, and there is a problem that the effect does not continue when being placed under high temperatures for a long time.
As a method for changing the properties of the material contacting parts to be used for an automobile interior part and an indoor mechanism part, a method for incorporating a silicone oil into an ABS resin and a method for incorporating an epoxy-containing olefin copolymer into an ABS resin, etc., have been proposed. For example, there have been disclosed a technology of incorporating an organosilicon compound into a PC/ABS resin (see patent document 1), a technology of incorporating a flame retardant, a flame retarding aid and a silicone oil into an ABS resin (see patent document 2), a technology of incorporating a silicone oil into a rubber reinforced polystyrene resin (see patent document 3), a technology of incorporating an alkali(earth) metal salt of an alkane sulfonate into an ABS resin (see patent document 4), and further, a technology of incorporating a modified polyorganosiloxane having at least one reactive group selected from among an epoxy group, a carboxyl group and an acid anhydride group into an ABS resin (see patent document 5).
However, an effect of reducing squeaking noises obtained by these methods is not said to be sufficient. Even if the effect of preventing squeaking noises is considerably exhibited immediately after molding, the durability of the effect is poor, and in particular, there is a problem that the effect deteriorates remarkably when being placed under high temperatures for a long time. Moreover, in recent years, there has been demanded, besides impact strength, ductile fracture, not brittle fracture having a fear of scattering splinters of a broken molded article in order to secure safety of crew members at the time of collision in usages of vehicle interior parts.